Dew is formed m calm and settled conditions generally associated with anti-cyclonic weather. During the night, the temperature falls and the air is unable to hold as much water vapour. The cooling which causes dew is the result of radiation during the night. The air-cools from the ground upwards, and if dew point is reached, condensation will occur.
The temperature at which condensation takes place.
The daily range of temperature or other weather elements.